Synthesis of Biobased Poly(butylene Furandicarboxylate) Containing Polysulfone with Excellent Thermal Resistance Properties.

A synthetic biopolymer derived from furandicarboxylic acid monomer and hydroxyethyl-terminated poly(ether sulfone) is presented. The synthesis involves 4,4'-dichlorodiphenyl sulfone and 4,4-dihydroxydiphenyl sulfone, resulting in poly(butylene furandicarboxylate)-poly(ether sulfone) copolyesters (PBFES) through melt polycondensation with titanium-catalyzed polymerization. This facile method yields segmented polyesters incorporating polysulfone, creating a versatile group of high-temperature thermoplastics with adjustable thermomechanical properties. The PBFES copolyesters demonstrate an impressive tensile modulus of 2830 MPa and a tensile strength of 84 MPa for PBFES55. Additionally, the poly(ether sulfone) unit imparts a relatively high glass transition temperature (Tg), ranging from 36.6 °C for poly(butylene 2,5-furandicarboxylate) to 112.3 °C for PBFES62. Moreover, the complete amorphous film of PBFES exhibits excellent transparency and solvent resistance, making it suitable for applications, such as food packaging materials.

High-Molecular-Weight and Light-Colored Disulfide-Bond-Embedded Polyesters: Accelerated Hydrolysis Triggered by Redox Responsiveness.

Disulfide bonds have attracted considerable attention due to their reduction responsiveness, but it is crucial and challenging to prepare disulfide-bond-based polyesters by melt polycondensation. Herein, the inherently poor thermal stability of the S-S bond in melting polycondensation was overcome. Moreover, poly(butylene succinate-co-dithiodipropionate) (PBSDi) with a light color and high molecular weights (Mn values up to 84.7 kg/mol) was obtained. These polyesters can be applied via melt processing with Td,5% > 318 °C. PBSDi10-PBSDi40 shows good crystallizability (crystallinity 56-38%) and compact lamellar thickness (2.9-3.2 nm). Compared with commercial poly(butylene adipate-co-terephthalate) (PBAT), the elevated mechanical and barrier performances of PBSDi make them better packaging materials. For the degradation behavior, the disulfide monomer obviously accelerates the enzyme degradation but has a weaker effect on hydrolysis. In 0.1 mol/L or higher concentrations of H2O2 solutions, the oxidation of disulfide bonds to sulfoxide and sulfone groups can be realized. This process results in a stronger nucleophilic attack, as confirmed by the Fukui function and DFT calculations. Additionally, the greater polarity and hydrophilicity of oxidation products, proved by noncovalent interaction analysis, accelerate the hydrolysis of polyesters. Moreover, glutathione-responsive breakage, from polymers to oligomers, is confirmed by an accelerated decline in molecular weight. Our research offers fresh perspectives on the effective synthesis of the disulfide polyester and lays a solid basis for the creation of high-performance biodegradable polyesters that degrade on demand.

Biobased Biodegradable Copolyesters from 2,5-Thiophenedicarboxylic Acid: Effect of Aliphatic Diols on Barrier Properties and Degradation.

The demand for sustainable development has led to increasing attention in biobased polyesters due to their adjustable thermal and mechanical properties and biodegradability. In this study, we used a novel bioderived aromatic diacid, 2,5-thiophenedicarboxylic acid (TDCA) to synthesize a list of novel aromatic-aliphatic poly(alkylene adipate-co-thiophenedicarboxylate) (PAATh) copolyesters through a facile melt polycondensation method. PAAThs are random copolyesters with weight-average molecular weights of 58400 to 84200 g·mol-1 and intrinsic viscosities of 0.80 to 1.27 dL·g-1. All PAAThs exhibit sufficiently high thermal stability as well as the highest tensile strength of 6.2 MPa and the best gas barrier performances against CO2 and O2, 4.3- and 3.3-fold better than those of poly(butylene adipate-co-terephthalate) (PBAT). The biodegradability of PAAThs was fully evaluated through a degradation experiment and various experimental parameters, including residue weights, surface morphology, and molecular compositions. The state-of-the-art molecular dynamics (MD) simulations were applied to elucidate the different enzymatic degradation behaviors of PAAThs due to the effect of diols with different chain structures. The sterically hindered carbonyl carbon of the PHATh-enzyme complex was more susceptible to nucleophilic attack and exhibited a higher tendency to enter a prereaction state. This study has introduced a group of novel biobased copolyesters with their structure-property relationships investigated thoroughly, and the effect of diol components on the enzymatic degradation was revealed by computational analysis. These findings may lay the foundation for the development of promising substitutes for commercial biodegradable polyesters and shed light on their complicated degradation mechanisms.

Sustainable Janus lignin-based polyurethane biofoams with robust antibacterial activity and long-term biofilm resistance.

Conventional antibiotic therapies have been becoming less efficient due to increasingly, and sometimes fully, antibiotic-resistant bacterial strains, sometimes known as "superbacteria" or "superbugs." Thus, novel antibacterial materials to effectively inhibit or kill bacteria are crucial for humanity. As a broad-spectrum antimicrobial agent, silver nanoparticles (Ag NPs) have been the most widely commercialized of biomedical materials. However, long-term use of significant amounts of Ag NPs can be potentially harmful to human health through a condition known as argyria, in addition to being toxic to many environmental systems. It is, thus, highly necessary to reduce the amount of Ag NPs employed in medical treatments while also ensuring maintenance of antimicrobial properties, in addition to reducing the overall cost of treatment for humanitarian utilization. For this purpose, naturally sourced antimicrobial polylysine (PL) is used to partially replace Ag NPs within the materials composition. Accordingly, a series of PL, Ag NPs, and lignin-based polyurethane (LPU) composite biofoams (LPU-PL-Ag) were prepared. These proposed composite biofoams, containing at most only 2 % PL and 0.03 % Ag NPs, significantly inhibited the growth of both Gram-positive and Gram-negative bacteria within 1 h and caused irreversibly destructive bactericidal effects. Additionally, with a layer of polydimethylsiloxane (PDMS) on the surface, PDMS-LPU-PL(2 %)-Ag(0.03 %) can effectively prevent bacterial adhesion with a clearance rate of about 70 % for both bacterial biofilms within three days and a growth rate of more than 80 % for mouse fibroblasts NIH 3 T3. These lignin-based polyurethane biofoam dressings, with shorter antiseptic sterilization times and broad-spectrum antibacterial effects, are extremely advantageous for infected wound treatment and healing in clinical use.

Design of 2,5-furandicarboxylic based polyesters degraded in different environmental conditions: Comprehensive experimental and theoretical study.

Nowadays, the promotion and application of aliphatic-aromatic copolyesters, such as poly (butylene adipate-co-terephthalate) (PBAT), are growing into a general trend. Although the structures of diacids exerted substantial impacts on degradation behavior, the underlying mechanisms have rarely been studied. In this work, 2,5-Furandicarboxylic acid was combined with succinic acid (PBSF), adipic acid (PBAF) and diglycolic acid (PBDF) to prepare three kinds of copolyesters. They showed unique degradation behaviors in buffer, enzyme environment and artificial seawater. These characteristics are closely related to the structural compositions of diacids. PBAFs displayed impressive biodegradability when catalyzed by Candida antarctica lipase B (CALB), while the more hydrophilic PBDFs exhibited faster hydrolysis in both buffer and artificial seawater. PBSFs, with hydrophobic and short segments, obtained a relatively slower rate of hydrolysis and enzymatic degradation. The reactivity sites and hydrolytic pathway were revealed by the combination of DFT calculation and Fukui function analysis. MD simulations, QM/MM optimizations and theozyme calculations showed that PBAF-CALB was prone to form a pre-reaction state, leading to the reduced energy barrier in the acylation process. This work revealed the effects of different structural features of diacids on polymer degradation and paved a way to design target biodegradable polymers in different degradation conditions.

Acid-triggered, degradable and high strength-toughness copolyesters: Comprehensive experimental and theoretical study.

The popularization and widespread use of degradable polymers is hindered by their poor mechanical properties. It is of great importance to find a balance between degradation and mechanical properties. Herein, poly(butylene terephthalate) (PBT) modified by SPG diol from 10% to 40 mol% were synthesized through a two-step polycondensation reaction. Chemical structures, thermal properties, mechanical properties, viscoelastic behavior and degradation of poly(butylene terephthalate-co-spirocyclic terephthalate) (PBST) were investigated. The SPG could toughen the copolyesters and the elongation at break of PBST20 was up to 260%. Moreover, the introduction of SPG enables to provide an acid-triggered degradable unit in the main chain. PBSTs copolymers maintain stable structures in a neutral environment, and the degradation under acid conditions will be unlocked. As tailoring the content of SPG, the degradation rate of the chain scission in response to acid stimuli will be adjusted. The acid degradation was proved to be occurred at the SPG units in the amorphous phase by DSC, XRD, GPC and 1H NMR tests. After the acid degradation, the hydrolysis rate will also be accelerated, adapting to the requirements of different degradation schedules. The plausible hydrolytic pathways and mechanisms were proposed based on Fukui function analysis and density functional theory (DFT) calculation.

High-performance two-dimensional montmorillonite supported-poly(acrylamide-co-acrylic acid) hydrogel for dye removal.

High-performance two-dimensional montmorillonite supported-poly (acrylamide-co-acrylic acid) hydrogel for dye removal was investigated. Montmorillonite cooperated with acrylamide and acrylic acid via polymerization, hydrogen-bond, amidation and electrostatic interactions to form the three-dimensional reticular-structured hydrogel with the free entrance for macromolecules. Adsorption tests revealed that the efficient removal (97%) for methylene blue at high concentration (200 mg/L) could be achieved via a small dose of hydrogel (0.5 g/L) within a short time (20 min). The excellent adsorption performance was profited from the electronegative surface and fully exposed reaction sites of two-dimensional montmorillonite, which could save the treatment cost and promote the removal effect compared with the conventional adsorbents. The adsorption process of methylene blue onto hydrogel could be fitted by both the pseudo-first-order and pseudo-second-order kinetics models, and the adsorption isotherm corresponded to the Sips model. The mechanism analysis based on Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy measurements illustrated that the reaction between carboxyl groups and methylene blue molecules as well as the cation-exchange enabled the hydrogel performing extraordinary adsorption efficiency.

Preparation of superhydrophobic polymeric film on aluminum plates by electrochemical polymerization.

6-(N-Allyl-1,1,2,2-tetrahydroperfluorododecyl)amino-1,3,5-triazine-2,4-dithiol monosodium (ATP) was used to prepare polymeric thin films on pure aluminum plates to achieve a superhydrophobic surface. The electrochemical polymerization process of ATP on aluminum plates in NaNO(2) aqueous solution and the formation of poly(6-(N-allyl-1,1,2,2-tetrahydroperfluorododecyl)amino-1,3,5-triazine-2,4-dithiol) (PATP) thin film were studied by means of optical ellipsometry and film weight. The chemical structure of the polymeric film is investigated using FT-IR spectra and X-ray photoelectron spectroscopy (XPS). Contact angle goniometry was applied to measure the contact angles with distilled water drops at ambient temperature. The experimental results indicate that the polymeric film formed on pure aluminum plates exhibits superhydrophobic properties with a distilled water contact angle of 153 degrees. The electrochemical polymerization process is time-saving, inexpensive, environmentally friendly and fairly convenient to carry out. It is expected that this technique will advance the production of superhydrophobic materials with new applications on a large scale. Moreover, this kind of polymeric thin film can be used as a dielectric material due to its insulating features.

A new organofunctional ethoxysilane self-assembly monolayer for promoting adhesion of rubber to aluminum.

Practical adhesion of rubber to aluminum is measured for various aluminum silanization treatments. In this study, 6-(3-triethoxysilylpropylamino)-1,3,5-triazine-2,4-dithiol (TES) was used as the coupling agent for preparing self-assembly monolayers (SAMs) on an aluminum surface. The structure and chemical composition of the SAMs were analyzed using Fourier transform infra-red spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The changes in the surface features of the aluminum surface due to TES treatment were investigated by atomic force microscopy (AFM). The adhesive properties of the silanized aluminum surface and EPDM rubber have been evaluated by a T-peel strength test. The results suggested that the Si-O-Al bonding at aluminum TES interface existed and a TES self-assembly monolayer was formed on the aluminum surface. More than 6.0 KN/m adhesion strength is obtained when the aluminum is silanized with 2.5 mmol/dm(3) TES, cured at 160 degrees C and vulcanized with EPDM rubber at 160 degrees C for 30 min. It is suggested that the TES self-assembly monolayer is bound to aluminum through its ethoxysilyl functional group, and the thiol function group is strongly crosslinked to EPDM rubber, respectively.

Hydrolysis behavior of regenerated celluloses with different degree of polymerization under microwave radiation.

This work studied the hydrolysis behavior of regenerated celluloses (RCs) with different degree of polymerization (DP) by using the catalyst of dilute acid under microwave radiation. Results showed that the DP had a considerable influence on hydrolysis of cellulose. The reactivity of RCs was significantly improved when DP was lower than 51. The highest sugar yield of 59.2% was achieved from RC with lowest DP of 23 at 160 °C for 15 min. But the lowest yield of 32.6% was obtained when RC with highest DP of 132 was used. Recrystallization of cellulose was found to hinder the further hydrolysis particularly with the high DP. The effect of recrystallization can be reduced by the decrease of DP of RCs. This research demonstrates that the DP of RCs plays a crucial role on hydrolysis and it provides a preliminary guide based on DP to find a suitable pretreatment method for cellulose hydrolysis.

Activation of corn cellulose with alcohols to improve its dissolvability in fabricating ultrafine fibers via electrospinning.

Water and four small molecular alcohols are respectively used to activate corn cellulose (CN cellulose) with the aim to improve the dissolvability in DMAc/LiCl. Among all these activated agents, monohydric alcohols are found to produce the optimal effect of activation in the whole process including of activating, dissolving, and electrospinning of CN cellulose. Meanwhile, well distributed fibers with the diameter of 500nm-2µm are fabricated in electrospinning. Understanding the activation effect of monohydric alcohols with water and polyhydric alcohols, the most effective activated agent is ascertained with the characteristics of small molecular size, low viscosity, and single functionality. This work is definitely initiated to understand the critical principle of CN cellulose in dissolving. Accordingly, a feasible methodology is also established to prepare ultrafine cellulose fibers with good morphology in electrospinning.

Responsive behavior of regenerated cellulose in hydrolysis under microwave radiation.

This work studied the responsive behavior of regenerated cellulose (RC) in hydrolysis under microwave radiation. Four types of RC with different crystallinity (Cr) and degree of polymerization (DP) are produced to evaluate the reactivity of RC by step-by-step hydrolysis. Results show Cr is the key factor to affect the reactivity of RCs. With hydrolysis of amorphous region and the formation of recrystallization, the Cr of RC reaches a high value and thus weakens the reactivity. As a result, the increment of cellulose conversion and sugar yield gradually reduces. Decrease of the DP of RC is helpful to increase the speed at the onset of hydrolysis and produce high sugar yield. But, there is no direct influence with the reactivity of RC to prolong the time of pretreatment. This research provides an accurate understanding to guide the RC preparation for sugar formation with relative high efficiency under mild reaction conditions.